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Author: Subject: What is this wierd pyrite
mrfeld
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[*] posted on 2-4-2011 at 10:53
What is this wierd pyrite




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hissingnoise
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[*] posted on 2-4-2011 at 11:17


Pyrite is a weird mineral . . .
This page from wiki shows something similar!

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Xenoid
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[*] posted on 2-4-2011 at 12:54


Pyrite is unstable in the presence of air (oxygen) and moisture. It breaks down to form a whole range of hydrated iron sulphate minerals as well as sulphuric acid. The sulphuric acid will react further with silicate minerals in the gangue to form other sulphates and also release SiO2. The gel like material you observe is probably a mixture of hydrated sulphate minerals and silica gel.

Pyrite is hard to preserve, and should be kept in a moisture free environment. I have seen pyrite "specimens" in collections which were just a pile of powder!

Edit: This paper gives some idea of the complex alteration products!

http://www.lpi.usra.edu/meetings/lpsc2008/pdf/1462.pdf


[Edited on 2-4-2011 by Xenoid]
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[*] posted on 2-4-2011 at 13:19
could be pyrite's unstable cousin


Markcasite White pyrite like pyrite FeS2

Yea old Dana sez —

Alt.— Marcasite being relatively unstable is easily altered.
Specimens disintegrate [easily!] with the formation of ferrous sulphate and sulphuric acid.

I keep mine (mostly Marcasite on wood) in a jar with CaCl2.

See Dana or some such for a simple chemical test to tell them apart.
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cyanureeves
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[*] posted on 2-4-2011 at 17:04


Pyrite is wierd. Not having ever seen platinum ore I thought I had struck it rich with some pretty silver looking pyrite I had secretly stashed away.My weak nitric acid wouldn't dissolve it so it made me think more so that I had platinum on my hands. Aqua regia had to be used and it make a bright orange red solution as it dissolved,this gave me enough confidence to do the heated spoon test. I put some grains on a spoon and passed it over a flame and it shot out like a bullet. I added some carbonate to the solution and am going to add acetone to make some sort of sweet smellin oil of iron out of the rust I now have.
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chemrox
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[*] posted on 2-4-2011 at 19:59


The photo looks more like galena than pyrite and the gangue material may be hydrous lead II hydroxide



"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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blogfast25
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[*] posted on 3-4-2011 at 06:59


And I've seen samples of pyrite crystals preserved in atmospheric conditions, without any degradation for decades...
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[*] posted on 3-4-2011 at 12:44


Quote: Originally posted by chemrox  
The photo looks more like galena than pyrite and the gangue material may be hydrous lead II hydroxide

A simple streak test will tell. La mineral is rubbed on a piece
of unglazed white porcelain. The sell 2" squares for this, however,
to prove you experimental bona fides you could break your favorite
coffee cup or a piece of your wife favorite porcelain ware — and use a broken edge.

Galena streaks lead gray.
Pyrite greenish-black.

Probable there dobe a borax bead test to distinguish them.


It is never toooo early to start you Christmas shopping
a pyrite sphere perhaps?!

http://tinyurl.com/3q6gr3h

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